Hardening AISI 1050 Steel 1

[rrossey]

Material:
AISI 1050, Strips cut from cold rolled .25” thick sheet
0.25” thick, 2” wide and 18” long
Grooves 0.05”deep machined on both flat surfaces

Requirement:
Harden to HRc 60 with a case hardening depth between 0.03” to 0.05”
The piece should be free from twist and bend (distortion after hardening) on visual inspection
(Bend less than 0.1” and Twist less than 2degrees on a full length of 18”)
Case hardening required on 14” length, with 2” length on both ends may or may not be hardened.

Process:
The process of hardening was done in a cyanide based salt bath for carburizing and quenching in brine. The piece was manually quenched and inspected for straightness and twist, while still hot enough to be corrected.

The operation was done by a Singapore company at nearby Indonesian island of Batam.
Now we propose to do this operation in North America without the use of salt bath furnace.

Production capacity required is about 100 pieces per day.

Proposed process:
To pack carburize the material in a box type electric furnace for 4 hours and let it cool.
To heat a piece by induction heater while the individual piece is held in a fixture at both ends and quench in brine, still being held in fixture to avoid bending and twisting.
The induction heating and brine quenching can be progressive, without heating the full length at one time.

Your comments and suggestions requested for:
1) What is the probability of success for the above process?
2) What are the alternatives available for the process?
3) When carburized steel is heated in an open atmosphere by induction heating, what should be the approximate time to heat the material without decarburizing the surface?

All your help in comments and suggestions are highly appreciated.

 

[arunmrao]

Are you certain about the grade of steel AISI 1050. this grade of steel is not amenable to case carburizing. Please check.

 

[rrossey]

Sure about the material
It is AISI 1050

 

[swall]

You should be able to easily obtain Rc 60 on this material without having to carburize prior to induction hardening. So, delete the carburizing step. As for the clamping and induction hardening, it should work. Either a water quench or polymer quench would work. You don't need brine and you don't want brine around electrical equipment.

 

[rrossey]

Thanks for the quench suggestion.

Regarding the carburizing, I am informed that for this product it is important that the Carbon potential on the surface should be raised to minimum 0.8% before hardening. What is the transformation taking place? I do not know about it, but like to have some info.

For Induction hardening the time to heat the product is about 20 to 25 seconds. During this heating time in air, what are the chances of decarburization on the surface?

 

[arunmrao]

If the surface carbon was the governing factor,you could have selected a steel like 8620,nicely case carburize and then harden. In my opinion,building up carbon from 0.5-0.8% must be an uphill task.

 

[swall]

Rrossey--It sounds like your customer has a requirement for .80 carbon surface, which, as Arunmrao points out, is pushing you to 8620 steel or other carburizing grade. This will need to be resolved before you consider induction hardening or alternative processing. Having said that, I can comment on the decarb. With induction hardening in air, you will get some mild scaling but no decarb of any consequence.